Early detection of breast cancer remains one of the most significant challenges in health care. The tactile breast imager (TBI) is a promising solution that electronically captures the sense of touch to provide a quantitative, sensitive, and permanent record of palpatory breast examination. Its inherent low cost, ease of use, and promising test results to date, give it great potential as an effective mass pre-screening tool for breast cancer detection. In Phase I, we successfully developed and tested a prototype device that showed sensitivity well beyond the manual palpation limit in a variety of test conditions. The device was tested on physical tissue models and demonstrated to robustly detect nodules of various sizes and subcutaneous depths. Advanced data processing algorithms were developed providing vivid 3-D images of the underlying mechanical tissue structure. In Phase II we will perform an initial clinical study to acquire raw image data and correlated lesion mechanical property data for use in refining the image processing and feature identification capabilities. We will concurrently build an advanced TBI prototype with substantially improved sensor performance. Clinical studies will be performed involving concurrent mammography / TBI imaging with qualitative comparative analysis between the modalities. We will conduct clinical development studies and build physical breast models to improve the data collection and lesion discrimination performance. The TBI will then be tested in a blinded clinical study to obtain statistically relevant measures of lesion sensitivity, specificity, and mechanical image quality. Appropriate regulatory testing will be conducted in order to prepare necessary engineering documentation for a FDA application.